Low Testosterone Shown To Increase Risk For Parkinson's

In a recent study, a drop in the testosterone levels of male mice caused them to manifest symptoms that appear to be very similar to those found in Parkinson's Disease. Male testosterone levels typically peak in the mid-30's and then decline around 1% each year thereafter. The decline can be made more sudden by other factors such as stress or other life events. Low testosterone has also been linked to an increased risk for Alzheimer's. Given that men are already known to be 1.5 times more likely to develop Parkinson's, the link to lower testosterone levels seems to make a lot of sense.

http://www.medicaldaily.com/articles/17863/20130728/mouse-study-shows-link-between-low-testosterone.htm